With computerization of automobiles in recent years, automobiles have come to be equipped with multilayer ceramic capacitors. Further, on-board capacitors for automobiles have been required to keep capacitor characteristics under severe conditions such as high temperatures and high voltages, in particular, keep leakage current and insulation resistance degradation suppressed at high temperatures.
The multilayer ceramic capacitor disclosed in Patent Document 1 is proposed as a countermeasure for this requirement. In this multilayer ceramic capacitor, dielectric layers have a main constituent represented by BaTi(1-x)ZrxO3+aRe+bM (where Re is an oxide of at least one rare-earth element of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y, and M is an oxide of at least one metal element of Mg, Al, Cr, Mn, Fe, Ni, Cu, Zn, and V).
Furthermore, the dielectric layers contain a Si element-containing compound to meet 0.2 parts by mass the Si element-containing compound 5.0 parts by mass with respect to 100 parts by mass of the main constituent with 1.000≤Ba/Ti≤1.450, 5≤100x≤30, 0.02≤a≤0.18, and 0.02≤b≤0.18, and grains have a core-shell structure composed of a core part and a shell part surrounding the core part.
Because the capacitor has the composition and microstructure mentioned above, the multilayer ceramic capacitor in Patent Document 1 can improve temperature characteristics of relative permittivity with grain ferroelectricity (piezoelectricity) kept low and electric-field-induced strain reduced.
In addition, the multilayer ceramic capacitor disclosed in Patent Document 2 is proposed as another countermeasure. In this multilayer ceramic capacitor, dielectric layers contain, as their main constituent, a barium titanate, and contain, with respect to 100 mol of the barium titanate, 5 to 15 mol of a constituent composed of BaZrO3 and SrZrO3, 3 to 5 mol of MgO, 4 to 6 mol of R2O3 (where R is at least one element of Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu), 0.5 to 1.5 mol of at least one of MnO, Cr2O3, Co3O4, and Fe2O3, and 2.5 to 4 mol of a Si-containing compound. Furthermore, when the previously mentioned constituent is represented by (1-x)BaZrO3+xSrZrO3, x is 0.4 to 0.9.
Further, the multilayer ceramic capacitor in Patent Document 2 has, even when the dielectric layers are reduced in thickness, a high relative permittivity under a high electric field intensity, and moreover, may have favorable temperature characteristics and reliability.
Patent Document 1: Japanese Patent Application Laid-Open No. 2009-35431
Patent Document 2: Japanese Patent Application Laid-Open No. 2011-207696